But Mr. Zawahiri, a surgeon and the scion of an upper-class Egyptian family, strikes many as haughty and droning with little of the ability Mr. bin Laden had to inspire. Irascible, he is given to fueling obscure ideological conflicts within jihadi ranks; Al Qaeda itself reportedly split into two factions before bin Laden’s death, with Zawahiri in charge of the spinoff, according to Pakistani intelligence officials.

Three decades ago, a member of Zawahiri’s Islamic Jihad group recognized his lack of leadership, reportedly telling him, “No matter what group you belong to, you cannot be its leader.”

The solemn Zawahiri, however, has weathered countless obstacles – bombing raids, assassination attempts, brutal imprisonment, and dissension within his own ranks – to wage war on America and its allies.

After formally joining forces with bin Laden in 1998, he steered the group’s overall strategy through the 2000 USS Cole bombing that killed 17 US sailors in Yemen, the 9/11 attacks, and the Iraqi civil war stoked by an Al Qaeda offshoot. In recent years, he delivered more audio and videotaped recordings than bin Laden himself.

A lack of popularity is unlikely to stall his plans for Al Qaeda’s future now, even if he faces an uphill battle to preserve the terrorist group that has been in decline and decentralizing for years.

While Al Qaeda has vowed to avenge bin Laden’s death with fresh attacks, the franchise’s grand vision is unlikely to regain the appeal it once held.

Bin Laden's worldview losing its appeal among former supporters

The victory of the mujahideen in Afghanistan in the 1980s, bin Laden was fond of saying, bankrupted the Soviet empire and led to its collapse. He repeatedly declared that attacks against the United States and its allies would likewise lead to the crumbling of what he saw as a godless, corrupt order.

In bin Laden’s eyes, 9/11 was the sort of moment that would inspire millions of Muslims and cause young men to flock to his cause.

And indeed, thousands of fighters converged on Iraq. Al Qaeda was developing a new core of radicalized fighters one country away from Saudi Arabia, the birthplace of Islam. Bin Laden was convinced that the US would be defeated there and that Muslims worldwide would reject secular politics.

But Al Qaeda’s atrocities in Iraq, where it killed thousands of civilians and stoked the Shiite-Sunni civil war in 2006-07, undercut the image of bin Laden’s group. Rather than millions in Egypt or Saudi Arabia being inspired, they were sickened by Muslims killing Muslims.

“The fact is, al-Qaeda had already been effectively marginalized within the mainstream of the Arab world long before bin Laden died,” writes Marc Lynch, a political science professor at George Washington University. “His death ... marks the end of an era of Arab politics which had already largely faded away.”

Arab Spring undermines bin Laden's ideology

A core part of bin Laden’s sales pitch was that only his jihad could remove Middle East autocrats from power. But in the last few years before his death, young Muslims were increasingly looking for solutions to their nations’ problems that didn’t involve restoring a medieval Islamic caliphate.

The popular uprisings in Egypt and Tunisia, which ousted two Western-backed dictators in quick succession, flatly disproved bin Laden’s worldview.

“We have clearly passed the Osama bin Laden era, and we are firmly into the Bouazizi era,” says Saudi columnist Hussein Shobokshi, referring to the young man whose self-immolation ignited the revolution in Tunisia that spread to the rest of the Arab world. “There is a grand difference between the two. One is from a very disturbed, annoying past, and one is belonging to a promising future.”

Indeed, a Pew poll conducted shortly before bin Laden’s death shows that Muslim “confidence that Osama bin Laden will do the right thing in international affairs” has plummeted in the past eight years – both in the Arab world and beyond. In the Palestinian territories, the number of supporters fell from 72 percent to 34 percent. In Pakistan, it dropped from 46 percent to 18 percent.

Al Qaeda’s “grandiose vision was completely wrong,” says Ray Takeyh, a Middle East scholar and senior fellow on the Council of Foreign Relations. “To the extent that regimes are being displaced, it’s being done by people power ... it has nothing to do with Al Qaeda.”

What will become of Al Qaeda now

Bin Laden’s dream of shaping societies through terrorism has failed. But that isn’t to say that attacks carried out by small cells of ideologically like-minded people will necessarily end.

Bin Laden’s relevance to recent global terrorist operations was limited, and offshoots of his group have long been operating on their own. The so-called Al Qaeda franchises in Iraq, Yemen, North Africa, and elsewhere share bin Laden’s austere and chauvinistic Salafi brand of Islam, but are free agents.